Geoengineering methods based on either direct carbon dioxide removal (CDR) from the atmosphere or solar radiation management (SRM) that curtails solar irradiation are campaigned for as technical solutions that would slow down the global temperature rise and climate change. Except for a few CDR methods, this does not receive much interest from policy-makers as a result of a lack of evidence on net advantages and decision-making challenges related to boundary-crossing effects, not to mention costs. An alternative, third geoengineering approach would be enhanced cooling by thermal radiation from the Earth's surface into space. The so-called atmospheric window, the 8–14 μm bandwidth where the atmosphere is transparent for thermal radiation indeed offers a “window of opportunity” for technology that enables sending out thermal radiation at rates that significantly exceed the natural process. This paper describes work that addresses this, with focus on technical devices that combine materials with the properties required for enhanced long wavelength (LW) thermal radiation heat transfer from Earth to space, through the atmospheric window. One example is a skylight (roof window) developed and tested at our institute, using ZnS windows and HFC-type gas (performing better than CO2 or NH3). Suggestions for several other system layouts are given.
Highlights
• Passive radiative cooling should be seen as geoengineering method, cooling Earth.
• The atmospheric window (8–14 μm) allows for heat transfer through the atmosphere.
• Choices of suitable materials with long wavelength transparency are limited.
• Experimental findings verified theoretical assessment and model simulation work.
• Passive radiative cooling during daytime still presents a considerable challenge.
Thank you very much Renaud,
In my opinion, a quite third large category of geoengineering could be described as “thermal conductance enhancement, to be located between the ground and our common heat sink, the space”.
It would include, of course, all the means of enhancing the thermal infrared emissions, as the quoted paper and the first two added links propose it.
It would also include any mean to enhance heat convection from the surface towards upper atmosphere layers, as does your paper to which your last link aims. This is a field where we have worked together some years ago, including for polar regions.
And it would include, as well, the deterioration or bypassing of natural efficient isolators such as the neat and beautiful air-rich snow blanket which, in winter, covers the polar regions. Two ideas have been proposed in this respect. First, the old paper by Zhou and Flynn, proposing to use wind energy to pump sea water from under the ice pack (where, due to the high thermal resistance of the ice pack, it would very slowly freeze by transferring its heat to the outer space), and spraying it into the freezing air just over the same ice pack. And second, a new idea by a Russian specialist of the permafrost. It would consist in increasing the number of herbivorous animals, such as reindeers, which would trample on the snow, sharply reducing its isolating power, and helping the permafrost to reach winter temperatures around, say, – 40 °C instead of – 10°C, hence being much better prepared to resist to summer heating and to prevent carbon (CO2 or CH4) leaking.
As you can see, all these quite different ideas have a common basis: the fact that, as the CO2 increase has the effect of increasing the thermal resistance between the ground and the outer space, creating or enhancing parallel heat conductors between part or all of the same interval, could be quite logical geoengineering ideas.
Best regards,
Denis Bonnelle.
De : Renaud de RICHTER <renaud.d...@gmail.com>
Envoyé : vendredi 20 juillet 2018 16:14
À : Carbon Dioxide Removal <CarbonDioxideRemoval@googlegroups.com>; geoengineering <geoengineering@googlegroups.com>; ron.zev...@abo.fi; marti...@abo.fi
Cc : Leon Di Marco <len...@gmail.com>; Denis.B...@normalesup.org
Objet : A 3rd, new and less intrusive geoengineering approach
Forwarded message from Denis Bonnelle.
2018-07-24 16:52 GMT+02:00 Bonnelle, Denis <denis.b...@crtc.ccomptes.fr>:
Thank you very much Renaud,
In my opinion, a quite third large category of geoengineering could be described as “thermal conductance enhancement, to be located between the ground and our common heat sink, the space”.
It would include, of course, all the means of enhancing the thermal infrared emissions, as the quoted paper and the first two added links propose it.
It would also include any mean to enhance heat convection from the surface towards upper atmosphere layers, as does your paper to which your last link aims. This is a field where we have worked together some years ago, including for polar regions.
And it would include, as well, the deterioration or bypassing of natural efficient isolators such as the neat and beautiful air-rich snow blanket which, in winter, covers the polar regions. Two ideas have been proposed in this respect. First, the old paper by Zhou and Flynn, proposing to use wind energy to pump sea water from under the ice pack (where, due to the high thermal resistance of the ice pack, it would very slowly freeze by transferring its heat to the outer space), and spraying it into the freezing air just over the same ice pack. And second, a new idea by a Russian specialist of the permafrost. It would consist in increasing the number of herbivorous animals, such as reindeers, which would trample on the snow, sharply reducing its isolating power, and helping the permafrost to reach winter temperatures around, say, – 40 °C instead of – 10°C, hence being much better prepared to resist to summer heating and to prevent carbon (CO2 or CH4) leaking.
As you can see, all these quite different ideas have a common basis: the fact that, as the CO2 increase has the effect of increasing the thermal resistance between the ground and the outer space, creating or enhancing parallel heat conductors between part or all of the same interval, could be quite logical geoengineering ideas.
Best regards,
Denis Bonnelle.
De : Renaud de RICHTER <renaud.d...@gmail.com>
Envoyé : vendredi 20 juillet 2018 16:14
À : Carbon Dioxide Removal <CarbonDiox...@googlegroups.com>; geoengineering <geoengi...@googlegroups.com>; ron.zev...@abo.fi; marti...@abo.fi
Cc : Leon Di Marco <len...@gmail.com>; Denis.B...@normalesup.org
Objet : A 3rd, new and less intrusive geoengineering approach
Very good paper (pay wall) from Zevenhoven, Ron, and Martin Fält.
"Radiative cooling through the atmospheric window: A third, less intrusive geoengineering approach." Energy 152 (2018): 27-33.
Unfortunately the authors forgot to cite previous similar proposals see here, here and here (open access).
Abstract
Geoengineering methods based on either direct carbon dioxide removal (CDR) from the atmosphere or solar radiation management (SRM) that curtails solar irradiation are campaigned for as technical solutions that would slow down the global temperature rise and climate change. Except for a few CDR methods, this does not receive much interest from policy-makers as a result of a lack of evidence on net advantages and decision-making challenges related to boundary-crossing effects, not to mention costs. An alternative, third geoengineering approach would be enhanced cooling by thermal radiation from the Earth's surface into space. The so-called atmospheric window, the 8–14 μm bandwidth where the atmosphere is transparent for thermal radiation indeed offers a “window of opportunity” for technology that enables sending out thermal radiation at rates that significantly exceed the natural process. This paper describes work that addresses this, with focus on technical devices that combine materials with the properties required for enhanced long wavelength (LW) thermal radiation heat transfer from Earth to space, through the atmospheric window. One example is a skylight (roof window) developed and tested at our institute, using ZnS windows and HFC-type gas (performing better than CO2 or NH3). Suggestions for several other system layouts are given.
Highlights
• Passive radiative cooling should be seen as geoengineering method, cooling Earth.
• The atmospheric window (8–14 μm) allows for heat transfer through the atmosphere.
• Choices of suitable materials with long wavelength transparency are limited.
• Experimental findings verified theoretical assessment and model simulation work.
• Passive radiative cooling during daytime still presents a considerable challenge.
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Russia building the tools, though not for cooling the planet!
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Russia building the tools, though not for cooling the planet!
Bru Pearce
Commercial and consulting www.envisionationltd.com
Climate messaging and reporting www.envisionation.co.uk
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